1. Field of the Invention
The present invention relates to aiming devices and, more particularly, to a method and system for sensing point of aim and rotation using optical energy.
2. Description of the Related Art
In general, aiming or pointing devices have been used in numerous different applications. Laser pointing devices, for example, are commonly used for gun sights or for "play" guns which are used with arcade games. Mechanical pointing devices (e.g., mouse) are also very popular. These known pointing devices are general purpose devices which are not capable of providing high precision aiming feedback for guns or other shooting apparatus.
Pointing devices which use radiated energy to communicate from a remote unit to a base unit are known. These known pointing devices are, however, unsatisfactory because they are not true three-axis pointing devices. U.S. Pat. No. 5,339,095, issued to Redford, describes a pointing device useful to control a computer system. The device is only a two-axis system which measures tilts left, right, up and down. A fundamental problem with this device is that the natural motion for a user of a pointing device is pointing, not tilting. U.S. Pat. No. 5,045,843, issued to Hansen, describes an optical pointing device used to provide cursor control on a display screen. This device is a two-axis system capable of measuring either tilts or translation of a camera with respect to a light source. Known pointing devices are unable to provide three-axis information; therefore, the uses of existing pointing devices are limited and not as flexible as users would like.
One particular application of an aiming device is a shooting practice apparatus. Shooting practice for various shooting apparatus, such as guns and bows, has become more popular in recent years, particularly when training for competitive shooting. Several aiming or pointing devices are or have been specifically made for shooting practice. U.S. Pat. No. 4,553,943, issued to Ahola et al, is an example of one such device. Ahola et al describes a method for shooting a narrow light beam at a target. A laser attached to the gun shines its beam of light towards the target. The target is made of glass and has a spot sensitive light detector directly behind it. The device determines where the shot would land on the target by the position where the light-spot lands on the target. Because bullets are not used, a shooter is able to practice his technique indoors. The method also makes use of continuous sensing so that it is possible to follow the aim of the gun during aiming and discharging.
The overall problem with existing shooting practice devices is that they do not provide satisfactory precision for those seeking to use the aiming device as a sports training aid. For the serious shooter who shoots at targets, high precision aiming and shot placement is desired so that he/she can analyze his/her shooting technique for flaws and thereby improve their technique. This demands that the aiming device provide high precision results. By high precision, it is meant accuracy of less than about 1 millimeter, preferably less than 0.1 millimeter at a range of 10 meters. Existing aiming devices, however, have been unable to satisfy the precision needs of serious shooters. Thus, there is a need for an aiming device which can reliably report high precision information to the shooter. This high precision information would include not only information about the shooters' aiming but also information as to where the shot would hit the target if actually shot.
A major reason why existing shooting practice devices cannot provide satisfactory precision for the serious shooter is that the existing shooting training devices are incapable of measuring and utilizing cant in computation of shot placement or as a source of feedback and analysis for the shooter. Cant, the rotation of a shooting apparatus about the line of fire, has significant impact on shooting accuracy and as such is an important component of shooting technique.
It is also advantageous that the aiming device be partially wireless. A wireless remote control is highly desirable in application areas such as television or computer control. As for shooting practice apparatus, the ability to provide mobile setup which avoids having to electrically wire to the shooting apparatus to a target is important because such wiring would be burdensome in most cases. For example, when using an aiming device to track one's aim onto a shooter's target lodged say 25 meters away, having to run 25 meters of wire from the shooting apparatus to the target would be burdensome.
For the shooting practice apparatus, it is also important that the shooting device be suitable for both "live" fire and "dry" fire. Some existing aiming devices for shooting do not support both "live" fire and "dry" fire. The ability to support both "live" fire and "dry" fire is advantageous because shooters are able to practice at home or in other locations where "live" fire is unsafe or impractical with "dry" fire. In addition, there are advantages to "dry" fire in serious training even at sites where "live" fire is practical.
Thus, there is a need for a three-axis aiming device which can provide high precision measurements.